1. Field of Invention
The present invention relates to an organic light emitting diode display device and a method of fabricating the same, and particularly, to an organic light emitting diode display device capable of improving color purity at boundaries of red, green and blue patterns by selectively forming thin films through a surface treatment, and a method of fabricating the same.
2. Background of the Invention
Flat panel display devices, such as organic light emitting diode (OLED), plasma display panel (PDP) and liquid crystal display (LCD) are being developed to replace cathode ray tube (CRT) which is heavy in weight and large in size.
Among those display devices, for example, the LCD and the OLED are provided with pixels each including a switching device, and a signal line including gate lines and data lines. The LCD and the OLED also include color filters or organic light emitting layers instead of the color filter to display an image with various colors.
Recently, in order to form color filters or organic light emitting layers, many new processing methods are being used to replace a traditional photolithography. A representative one is an inkjet printing method.
The inkjet printing is a method in which a shielding member, such as a black matrix or the like, is disposed on an insulating substrate, openings corresponding to pixels are formed at the shielding member via an exposure process and a development process, and ink droplets for a color filter are dispensed in the openings.
The formation of the color filters by adapting the inkjet printing method does not require processes of coating, exposure, development and the like, which allows a reduction of materials required for each process and a simplification of the whole fabrication process.
However, the process of forming the shielding member, namely, a partition wall which is performed prior to applying the inkjet printing method having such advantages requires the exposure process and the development process depending on an existing photolithography technique.
An organic light emitting diode display device according to the related art having a partition wall formed by using the photolithography technique will be described as follows with reference to FIGS. 1 and 2.
FIG. 1 is a planar view of an organic light emitting diode display device fabricated by using an inkjet printing method according to the related art.
FIG. 2 is a cross-sectional view taken along the line II-II of FIG. 1, which schematically shows an organic light emitting diode display device according to the related art.
As shown in FIG. 1, the organic light emitting diode display device according to the related art may comprise a substrate 11, an anode electrode 13 disposed on the substrate 11, a partition wall 15a formed on the anode electrode 13 and having openings corresponding to the number of pixels, a plurality of red R, green G and blue B organic light emitting layers 23a, 23b and 23c formed on the openings of the partition wall 15a, and cathode electrodes 25 formed on the organic light emitting layers 23a, 23b and 23c. 
Here, the partition wall 15a may improve brightness by blocking light leaked through a space between neighboring pixels, and may keep inks of color filters or organic light emitting layers during a fabrication process.
A fabrication method of the organic light emitting diode display device according to the related art having such configuration will be described with reference to FIGS. 3a to 3e. 
FIGS. 3a to 3e are cross-sectional views showing fabrication processes of the related art organic light emitting diode display device.
As shown in FIG. 3a, first, a conductive material is deposited on a substrate 11 to form an anode electrode 13 of the organic light emitting diode display device.
An insulating layer 15 is deposited on the anode electrode 13 by a certain thickness, and then a photosensitive layer 17 is coated thereon.
Then, as shown in FIG. 3b, exposure and development processes are performed using a photolithography technique to selectively pattern the photosensitive layer 17, thereby forming photosensitive layer patterns 17a. 
As shown in FIG. 3c, the insulating layer 15 is selectively removed by using the photosensitive layer patterns 17a as blocking layers, so as to obtain a partition wall 15a having openings where a plurality of organic light emitting layers are defined.
As shown in FIG. 3d, after removing the photosensitive layer patterns 17a, red R, green G and blue R organic light emitting solutions are sequentially dispensed into the openings of the partition wall 15a through inkjet dispensing units 19a, 19b and 19c by an inkjet printing method, so as to form R, G and B organic light emitting layers 23a, 23b and 23c, respectively.
Here, the inkjet dispensing units 19a, 19b and 19c may be used simultaneously or sequentially.
That is, a particular order is not required to dispense the R, G and B organic light emitting solutions, which means that any solution can be dropped first.
As shown in FIG. 3e, after forming the R, G and B organic light emitting layers 23a, 23b and 23c, a metallic material is deposited on the partition wall 15a having the organic light emitting layers 23a, 23b and 23c formed thereon.
The metallic layer is selectively patterned to form a cathode electrode 25 with respect to the anode electrode 12.
As mentioned above, several problems may occur in the organic light emitting diode display device and the fabrication method thereof according to the related art.
In the organic light emitting diode display device and the fabrication method thereof according to the related art, each organic light emitting solution for the color filters dispensed into the openings between the partition walls is a liquid crystal compound containing pigment, solvent, and other dispersing agents.
Accordingly, it is very difficult to dispense ink droplets on a desired point with a desired amount in a fluid state. Also, it is difficult to measure a misalignment, such as at which point ink droplets are dispensed far away from a desired drop point, based on the shape of the ink droplet in the opening.
In particular, since such dispensed ink droplet freely spreads out, it may be difficult to determine a point where ink droplet is mis-dispensed based on the spread shape of ink droplet.
As a result, the mis-dispensed ink may spread on the partition wall between neighboring organic light emitting layers, and additionally degrade the display characteristic of the display device.
Also, the time taken by drying each organic light emitting solution and the viscosity of each organic light emitting solution may be different. Such difference may cause non-uniformities of a thickness of an organic thin film at the same pattern and a degradation of color impurity.
Furthermore, the inkjet printing method may not be appropriate for forming fine patterns of several micrometers (μm), and should typically form partition walls for dividing each pattern in order to form desired thin films on a substrate. Also, the inkjet printing may additionally require a process of constructing a partition wall and a process of removing the partition wall.
Thus, due to the additionally required partition wall-forming process and the partition wall-removing process, the whole fabrication process may become more complicated, which increases fabrication cost.